Pressure fed lubricating system



Feb. 28, 1939. D. w F. D PAUL ET AL 2,149,068

PRESSURE FED LUBRICATING SYSTEM Filed June 22, 1937 2 SheetS- Sheet l awn/we Fig.5.

\ fin Feb. 28, 1939. D. w D PAUL ET AL 2,149,068

PRESSURE FED LUBRICATING SYSTEM Filed June 22, 1937 2 Sheets-Sheet 2 Fig. .5.

illlllllll Patented Feb. 28, 1939 UNITED STATES PRESSURE FED LUBRICATING SYSTEM David Wiiiett Fieetwood Dlllin Paul, London, and Cyril Llewellyn Bees and George Babel-t Winchester Lush, Halt-inn, England Application June 22, 1931, Serial No. 149,712 In Great Britain November so, me

19 Claims. (Cl. 123-196) This invention relates to pressure fed lubrication systems, more especially, although not exclusively, for internal combustion engines both of the stationary kind and also such as are used on land, sea and air vehicles.

The principal object of the invention is to employ an electric switch responsive to, and actuated by, the pressure in the 011 system, so that when the oil pressure drops below a safe minimum, the switch is operated to switch oi! the ignition and/ or to afi'ord a visible, audible or other signal or warning to the driver or operator. (The term oil shall be construed herein to mean any suitable lubricant.) Such a device may also be made to serve the purpose of avoiding discharge of the battery in the event of the ignition switch being left on inadvertently, for the reason that on the engine stopping the oil pressure drops towards zero, whereupon the switch breaks the ignition circuit upon the predetermined minimum pressure being attained.

The expression warning in this specification shall be construed to include not only a visual, audible or other signal to the driver, but also any automatic operation or action which directly or indirectly slows down, speeds up or stops (temporarily or otherwise) the apparatus with which the lubrication system is associated.

The stopping of the engine constitutes the most emphatic warning. In the case of a spark-ignition engine, the ignition may be switched off only partially, or temporarily, or again intermittently, so as to produce a noticeable mis-firing. In the case of a compression-ignition engine, the fuel injection may be regulated or cut-ofi.

As hitherto constructed, the pressure responsive switch has been set to cut out at a definite pressure, which in practice has sometimes been a relatively low pressure, e. g. about $4 lb. per sq. in. A

low setting has been utilized first to enable the engine to be started (that is to say the switch must cut in at the low oil pressure attained when starting the engine on the starting motor or handle) and secondly to permit slow-running and ticking-over.

It is evident that a safe minimum oil pressure for slow and light running is not necessarily safe when the engine is more heavily stressed or is running at higher speeds and consequently a pressure operated switch cutting out at a fixed pressure does not wholly safeguard the engine against damage arising from lubrication failure, including a drop in oil pressure due to the lowering of the oils viscosity.

The object of this invention is to provide an improved apparatus which will overcome the disadvantages mentioned, whilst retaining the sensitivity required for operating at starting and idling speeds.

According to this invention there is employed 5 the method of providing the operator or driver with a warning of oil shortage or failure of proper lubrication pressure consisting in the inclusion in the 011 system of a pressure responsive switch capable of actuating the warning device when the 10 oil pressure is insufficient, the pressure at which the said switch operates being automatically variable according to the requirements of the engme.

The invention moreover embraces a pressure 15 operated switch for use with a pressure fed lubrication system wherein the cut-out pressure is automatically varied with .the demands of the engine.

The invention also-includes in a pressure fed oil 20 system, the combination with an electric switch responsive to oil pressure and capable oi'operating a warning device, of a suction operated control device, which is adapted to vary the pressure at which the switch operates the warning device 25 according to the speed at which the engine is run.

The invention moreover includes the combination with an electric switch responsive to oil pressure, of a control device sensitive to the speed of the engine and adapted to vary the pressure at 30 which the said switch operates.

The invention will now be described with reference to the accompanying drawings, wherein:-

Fig. 1 shows a sectional elevation of a switch;

Fig. 2 shows a plan view thereof; 35

Fig. 3 shows a sectional elevation of a modified detail of construction;

Fig. 3a shows a plan view thereof;

Fig. 4 shows a sectional elevation of another modified detail of construction; 40

Fig. 5 shows a diagrammatic installation in accordance with the invention;

Fig. 6 shows a sectional elevation of another modified detail of construction, and 45 Fig. 7 shows a sectional elevation of yet another modified detail of construction.

Referring first to Figs. 1 and 2, the apparatus comprises three sections A, B and C. The section B constitutes a central chamber in which are mounted fixed contact members I and 2 electrically coupled to terminals 3 and 4 located on the outside of the casing 5. With the fixed contact members there co-operates a movable member 6 which is urged away from the fixed contact 55 members I and 2 by a spring I whereby the contacts are kept in the broken or "off" position.

The spring I bears at its upper end against a partition l9, between the chambers A and B, and at its lower end against an insulating plate 1a. provided with a raised rim lb and fitted into a recess in the upper surface of the contact mem- 'beri.

Below the section B, which constitutes 'i'g'contact chamber, is located the section C, co 'itut- G contains a flexible diaphragm 8 to the lower side of which pressure is admitted from a lubrieating system, such as a pump 9 (Fig. 5), which is connected by a pipe III to a suitable connection II at the bottom of the chamber C.

The dividing wall l2 between the contact chamber B and the pressure chamber is apertured at l3 to receive a headed plunger l4, l of insulating material, of which the headed portion I5 is located within a recess l8 in the under-face of the dividing wall l2.

The pressure chamber is preferably dished at the bottom as indicated at H, to provide a space for allowing oil to enter the pressure chamber 0 underneath the diaphragm 8.

When oil pressure is admitted below the diaphragm 8 from the pump 9, the diaphragm 8 is pressed upwardly and carries with it the plunger l4, l5 so that the headed portion l5 enters the recess I6 and the outer surface thereof lies fiush with the surface of the wall l2. In this position the headed portion l5 forms a continuation of the surface of the wall |2 so that a relatively smooth face is presented to the diaphragm 8. The diaphragm is thus supported against fracture or mutilation which might occur if high pressures were exerted on the diaphragm 8 from below.

The upper end l4 of the plunger l4, l5 bears against the movable contact member 8 in such a manner that when the plunger l4, I5 is in its raised position the movable contact 6 bears against the fixed contacts I and 2 so that the switch is closed.

Above the contact chamber B is located the section A constituting a suction chamber. The suction chamber contains a diaphragm I 8 of fiexible material. The dividing wall l9 between the contact chamber 13 and the suction chamber A is apertured at 28 to receive a push rod 2|, of insulating material, the lower end of which bears against the upper end of the plunger H or the movable contact member 6 or both against the plunger l4 and the contact member 8. If desired the plunger I4 and the push i'od 2| may be formed as a single element and the members 6 and la fitted therein. The upper end of the push rod 2| engages with a circular plate 22 which in turn bears against the diaphragm l8, the diameter of the circular plate 22 being almost as large as the diaphragm l8 so as to afford a good support therefor. If desired the push rod 2| and the plate 22 may be formed integral.

The downward movement of the plate 22 is limited by a stop formed by a boss 23 on the dividing wall l9. The stop is such that when the plate 22 and push rod 2| are in their lower position they just hold the movable contact 6 away from the fixed contacts I and 2 thus preventing undue pressure from being exerted on the diaphragm 8. The space 24 above the diaphragm l8 in the suction chamber A is vented to the atmosphere through an apertured plug 25, the passage through the plug being preferably adjusted by means of a screw 28.- The space 21 below the diaphragm 8 in the suction chamber A is connected with a source of suction from the engine, e. g. the mixture passage of a carburettor, on the air-intake side of the throttle valve 28 (Fig. 5)

.by'a pipe 29. A needle valve 29a may also be fitted to the pipe 29 for the purpose of adjusting the suction action on the diaphragm l8. The end of the pipe 29 leading into the air intake 28a is preferably in the form of a beak 2917, so cut away as to afford a suction effect.

As the engine speeds up the greater will be the suction in the suction chamber A below the diaphragm l8 so that the plate 22 and push rod 2| will tend to move downwardly in opposition to the action of the diaphragm 8 and the other parts associated therewith such as l4, I5. Thus at higher engine speeds a proportionally higher pressure will be required in the lubricating system to keep the contacts 6, I, 2 closed. When starting or idling, however, a relatively small oil pressure on the diaphragm 8 will suffice to close the switch or to keep the switch closed.

It will be realized that not only lack of oil, but also overheating or dilution of the oil, may be responsible for a drop in the oil pressure below a safe minimum for a given engine speed.

The various pressure and/or suction effects may be rendered adjustable and the various vents may be calibrated or rendered adjustable to set or maintain the device correctly for the purpose in view. The ratio between the pressure and suction effects may be adjusted by varying the effective areas of the respective diaphragms and/or plungers or plates.

The diaphragms 8 and I8 may be of oil-proof, impervious and very flexible non-metallic material and may be clamped in position round their peripheries between the component parts as shown in Fig. 1.

In a modified form of construction the contact member 6 may be of insulating material and be provided with a conducting ring in its upper surfaede 2for co-operation with the fixed contacts an Such parts as are necessary may be of insulating material.

The various sections A, B and C are secured together in any suitable manner for example by means of bolts 30.

In the modification shown in Fig. 3 the section A in Fig. 1 is replaced bya section A in which is located a plunger 3| formed integral with a plate 32 both of insulating material. The downward movement of the plate 32, and thus of the plunger 3| is limited by the boss 23' of the bottom plate I9 of the section A'. The plunger 3| is adapted to co-operate with the movable contact plate 6 (Fig. 1) in the manner described in connection with Fig. 1. The plate 32 is adapted to be actuated by a spring-pressed member 33 which is housed in a screw-plug 34 mounted in a screwcap 35 screwed into the stoppla'te 36 of the'section A. The screw-plug 34 is secured in the end of a lever 31 by a grub screw 38. The lever 31 is adapted to be actuated by a speed governor, not shown, by mechanism including a link 31a. The thread of the screw-plug 34 and the co-opera-ting thread of the screw-cap 35 are of quick pitch so that a relatively small movement of the lever 31 produces a considerable axial movement of the screw-plug 34. The speed governor acting on the screw-plug and thus on the plunger 3| has the same function as the suction action on the diaphragm l8 in F18. 1.

Fig.4showsaiurthermdificatimofthcse0- tionAinl igl. Inthismodificationthesection A" contains a bi-metaliic strip 55 which is located between-aterminal andapiunger 4|,ot

insulating material. The terminal 45 passesthrough insulation washers 45' and 45" fitted in a metalboss45d. Theterminal 45isinthe circuit 01' a separate dynamo, or on an auxiliary winding of the existing dynamo, so that the bi-metallic strip 59 is heated in accordance with the variation oi the speed of the dynamo, by means of a heating coil 59' one end of which is connected to the strip 59 and the other end of which is connected to the boss 45a. Thus the circuit from the dynamo is through the terminal 45, the strip 59, the heating coil 55' to earth through the boss 45a. and thence to the earthed pole of the dynamo. The connection of the strip 55 and heating coil 55' to a separate winding on the existing dynamo, or to a separate dynamo, is necessarily adopted as otherwise the cut out on the existing y amo would limit the voltage output at high speeds and consequently the amount of current passing through the strip 59 and heating coil 55' would not be proportional to the speed of the dynamo which is proportional to the speed of the engine.

The plunger 4| which passes through the boss 23" of the bottom plate l5" oi the chamber A", co-operates with the movable contact 5 in the same manner as above described in connection with the push rod'2l (Fig. 1) and the plunger 3| (Fig. 3). When thus the strip 55 is heated it tends to expand so as to apply pressure to the plunger 4|. It is, however, prevented from expanding unless the plunger 4| can move downwardly when there is insufilcient pressure on the diaphragm 5.

The apparatus described in the preceding figures may be inserted in any suitable electrical circuit to operate a signal or to give a warning. For example the device may be associated with the normal ignition circuit of an internal combustion engine as is indicated for example at 42 in Fig. 5. The terminal 5 is connected through a lead 43 to a coil 44 connected by a lead 45 to earth at 41, whilst the terminal 4 is connected through lead 54, contact 45, lead 55, ignition switch 5| to the ignition circuit 52. When the device 42 is not required for operation the switch 49 is brought into engagement with the contact 45 whereby the device 42 is short-circuited and the line 45 and coil are connected through switch 49 and contact 45 to the lead 50. When, however, the device is to be used the switch 49 is moved away from the contact 45 in which case the ignition circuit is as follows: earth 41, lead 45, coil 44, lead 45, terminal 3, fixed contact movable contact 5, fixed contact 2, terminal 4, lead 54, contact 45, lead 59, switch 5| and lead 52.

In Fig. 5 there is also shown an oil supply system for connection to the apparatus 42 by the pipe HI. In this case the oil pump 9 is furnished with two inlets 55 and 55 depending into the oil 51 in the sump 55 to different levels. The lower inlet 55 is at a pointcorresponding with the safe minimum oil level whilst the upper inlet 55 is located at a point corresponding to the level of oil at which it is desired to give a warning oi approaching shortage. A- tap, valve or similar device is fitted to the inlets 55, 55 which is adapted to be controlled by a link 59 and a lever 59 pivotally mounted at 5|. The lever 55 is adapted to be operated from the driver's seat.

In operation, after the sump 55 has been filled,

theinletllisopenedandtheinletflcioaedthe enlineisnmuntil theoillevelialls the ieveloitheinlet55.-Whenthisoccursthepump 5 no longer supplies sufiicient oil to maintain proper lubrication pressure so that the diaphragm 5 drops and the movable contact 5 moves awayirom the fixed contacts and 2 whereby the ignition circuit 52 is opened thus switching oil! the engine. When the driver receives this warning he operates the tap or valve controlling the inlets 55, 55 by actuating the lever 55 so as to close the inlet 55, and open the inlet 55, so that on re-starting the engine the pump now sucks oil through the lower inlet 55.

The driver then knows that he has in eiiect a reserve supply of oil. When the level falls below the second inlet 55 the driver is given a final warning by the engine stopping again because the pump 5 no longer supplies sufiicient oil to maintain the proper lubrication pressure with the result that the diaphragm 5 drops. The driver must then replenish the sump 55 with fresh oil, when the valve is again moved into the position in which the inlet 55 is open and the inlet 55 closed.

The operation of the valve co-operating with the inlets 55, 55 may be associated with an oil filler cap so that the latter can only be opened for filling the sump 55 with oil when the inlet 55 is opened. For this purpose the cap 52 fitted over the oil filling pipe 53 has mounted above this a bell-crank lever 54, 55 pivotally mounted at 55. The arm 54 is adapted to extend over the filler cap 52 when the inlet 55 is closed, whilst the arm 55 is connected to the lever 55 by a link 51. The links and levers may be replaced by any equivalent mechanism.

The position of the .various parts as shown in full lines in Fig. 5 corresponds with the closed position of the inlet 55 and the open position of inlet 55 whereas the chain-dotted position of the parts corresponds with the inlet 55 fully open and the inlet 55 closed and enabling the cap 52 to be removed for filling the sump with oil. It will, however, be understood that the cap 52 may be omitted in which case the arm 54 of the lever may constitute a cap for the filler pipe 55, or may serve to prevent access to the filler pipe 55 when in the full line position. In order to supply oil to the sump it is always necessary to move the system into the chain-dotted position, which is done by the driver, and the system is then in a position to give the preliminary warning should the oil level sink below the inlet 55.

Fig. 6 shows a further modification in which the suction chamber A in Fig. 1 is replaced by a pressure chamber A'. This arrangement dlfiers from Fig. 1 in that the air inlet 25 and the suction pipe 29 are omitted, and there is provided a tubular member 59 for connection to an additional oil pump whereby the diaphragm I5 is subjected to a constant oil pressure for given revolutions per minute. The diaphragm I8 is consequently always subjected to oil pressure from the said additional oil pump, which is operated at a smaller output than the normal oil pump.

Alternatively the eifective area of the diaphragm I5 and/or the plate 22 is constructed of such a size as to reduce the effective pressure on the push rod 2|. The said additional pump does not feed the lubricating system but only applies pressure to the diaphragm l5 according to R. P. M. and always has ample oil. It is provided with an overfiow and release valve which automatically prevent it from building up too much'pressure.

1 plate 22' are protected against damage by excessive pressures in the same manner as in the pressure chamber (Fig; 1).

We claim:

1. In a pressure ted lubrication system associated with an ignition circuit, the combination comprising a contact chamber, fixed and movable contacts in said chamber, said contacts being included in said'ignition circuit, a pressure chamber connected to the lubricating system, an element mounted in said pressure chamber, said element being responsive to variations in lubricant pressure and adapted to actuate said movable contact, a third chamber, and an element in said third chamber adapted to counteract the action of the element in the pressure chamber, the

element in the last mentioned chamber being subjected to fluctuations resulting from the variation in speed of the engine.

2. In a pressure fed lubrication system associated with an ignition circuit, the combination comprising a contact chamber, fixed and movable contacts in said chamber, said contacts being included in said ignition circuit, a pressure chamber connected to the lubricating system, an element mounted in said pressure chamber, said element being responsive to variations in lubricant pressure and adapted to actuate said movable contact, a third chamber, a diaphragm located in said third chamber, said diaphragm being opera- -tively associated with said movable contact, said diaphragm being exposed on one side to atmospheric pressure and on the other side to the suction of the engine.

3. In a pressure fed lubrication system associated with an ignition circuit, the combination comprising a contact chamber, fixed and movable contacts in said chamber, said contacts being included in said ignition circuit, a pressure chamber connected to the lubricating system, an element mounted in said pressure chamber, said element being responsive to variations in lubricant pressure and adapted to actuate said movable contact, a third chamber, a diaphragm located in said third chamber, said chamber being connected on one side of the diaphragm to the atmosphere through an adjustable vent and on the other side of said diaphragm being subjected to a suction action, said diaphragm being operatively connected to said movable contact.

4. A switch device for operative association with the ignition circuit of an internal combustion engine and the pressure fed lubrication system thereof, comprising three chambers secured together, a diaphragm mounted in one of said chambers, said diaphragm being exposed to the pressure of lubricant, a pair of fixed contacts in a second chamber, said fixed contacts being included in said ignition circuit, a movable contact in said second chamber, said movable contact being adapted to co-operate with said fixed contacts, a partition wall between said first and second chambers, said partition wall having an aperture and recess therein, a headed plunger movably mounted in said aperture and recess, said headed plunger when engaging with said 'recess having its surface flush with said partition,

' said headed plunger being adapted to be actuated by said diaphragm and bearing against said movable contact, a third chamber, a partition wall 75 between the second and third chambers, an aper- .screwed boss.

tured' boss on said last mentioned partition, a push rod movablyimounted in said boss, 9. spring between said last mentioned partition and said movable contact, a plate in said third chamber, said plate being adapted to be actuated by said pushrod, a diaphragm in said third chamber and co-operating with said plate, said third chamber having an adjustable air vent on one side or said diaphragm, and-means of communication with suction means connected to the other side 01 said.

pressure of lubricant, a pair oi! fixed contacts in a second chamber, said fixed contacts being included in said ignition circuit, a movable contact in said second chamber, said movable contact being adapted to co-operate with said fixed contacts, a partition wall between said first and second chambers, said partition wall having an aperture and recess therein, a headed plunger movably mounted in said aperture and recess, said headed plunger when engaging with said recess having its surface flush with said partition, said headed plunger being adapted to be actuated by'said diaphragm and bearing against said movable contact, a third chamber, a partition wall between the second and third chambers, an apertured boss on said last mentioned partition, a push rod movably mounted in said boss, a spring between said last mentioned partition and said movable contact, a plate secured to said push rod, a cap in said third chamber, a screwed boss in said cap, said cap having an internal thread for co-operation with the thread on said screwed plug, the co-operating threads being of quick pitch, a spring actuated member between said screwed boss and said plate, and a govemor-actuated lever secured to said 6- A switch device for operative association with the ignition circuit of an internal combustion engine and the pressure fed lubrication system thereof, comprising three chambers secured together, a diaphragm mounted in one of said chambers, said diaphragm being exposed to the pressure of lubricant, a pair of fixed contacts in a second chamber, said fixed contacts being included in said ignition circuit, a movable contact in said-second chamber, said movable contact being adapted to co-operate with said fixed contacts, a partition wall between said first and second chambers, said partition wall having an aperture and recess therein, a headed plunger movably mounted in said aperture and recess, said headed plunger when engaging with said recess having its surface fiush with said partition, said headed plunger being adapted to be actuated by said diaphragm and bearing against said movable contact, a third chamber, a partition wall between the second and third chambers, an apertured boss on said last mentioned partition, a push rod movably mounted in said boss', a spring between said last mentioned partition and said movable contact, a head on said push rod, a terminal element'in said third chamber, and a bi-metallic strip between said terminal and said head.

A warning device associated with the ignition system and pressure fed lubrication system of an internal combustion engine for the purpose specified comprising a pressure responsive switch in said ignition circuit, and means for automatically adjusting the pressure at which said switch operates.

8- A warning device associated with the ignition system and the pressure fed lubrication system of an internal combustion engine comprising apressure operated switch in'said ignition circuit, means for connecting said switch to said lubrication system and means for automatically varying the cut out pressure in accordance with the demands of the engine.

9. A warning device adapted to be associated with the pressure fed lubrication system of an internal combustion engine comprising an electric switch responsive to oil pressure in said lubricating system, warning means operable by said switch, and a suction operated control device associated with said switch, said control device being adapted to vary the pressure at which the switch operates the warning means according to the speed at which the engine is run.

10. A warning device adapted to be associated with the pressure fed lubrication system of an internal combustion engine comprising an electric switch responsive to oil pressure in said lubricating system, warning means operable by said switch, and a control device associated with said switch, said control device being sensitive to the speed of the engine and adapted to vary the pressure at which said switch operates.

11. A warning system comprising in combination a switch device, means for connecting said device to an engine whereby said device is subjected to the suctionof the engine, an oil sump, a pump located in said oil sump, means of communication between said pump and said switch, whereby said switch is subjected to the pressure of oil delivered by said pump, said pump having two inlets arranged one above the other, the lower inlet being at the minimum allowable oil level in said sump, means for alternately obturating said inlets, an ignition circuit including a source of current, a second circuit including said switch a second switch included in said ignition circuit, said second switch in one position serving to short circuit the first mentioned switch, and in a second position serving to bring said seuiiond switch into series with said ignition circ t.

12. A warning system according to claim 11, including a filling pipe for said sump, closure means for said pipe. and means connecting said closure means to the means for controlling the upper inlet of said pump.

13. A warning system according to claim 11, including a filling pipe for said sump, a closure cap fitted on said filling pipe, a pivotallymounted bell-crank lever, said bell-crank lever in one position serving to prevent said filling closure cap being removed and in a second position permitting iree removal 01' said cap,- and means for connecting said bell-crank lever to the means for controlling the upper inlet of the pump.

14. A warning system according to claim 11, including a valve for controlling the upper inlet,

a pivotally mounted bell-crank lever, a link to connect said valve to said bell-crank lever, said bell-crank lever when in one position exposing said inlet and in a second position closing said inlet.

15. In a pressure ied lubrication system associated with a warning circuit, the combination comprising a spring loaded switch included 'in said circuit, a pair of pressure responsive members adapted to co-operate with said switch, one of said pressure responsive means being connected to said lubrication system and being adapted to close said switch when a predetermined pressure obtains in the lubrication system, said second pressure responsive means being controlled in accordance with the speed of a prime mover, the resultant action of said pressure responsive members controlling the opening and closing of said switch.

16. In a pressure fed. lubrication system associated with a warning circuit, the combination comprising a spring loaded switch in said warning circuit, said switch tending normally to open, a pressure responsive member connected to said lubrication system, said pressure responsive member being adapted to co-operate with said switch, an element adapted to co-operate with said switch, said element being adapted to counteract the action of the pressure responsive member, said element being subjected to fluctuations resulting from the variation in speed of a prime mover.

17. A lubrication system according to claim 16, wherein the element is subjected to the suction action of an engine, means being provided for adjusting said suction action.

18. A lubrication system according to claim 18, wherein the element is subjected to the suction action of an engine, means being provided for adjusting said suction action, said means including a needle valve located in the suction pipe between the engine and said element.

19. In a pressure ted lubrication system associated with a warning circuit, the combination comprising a contact chamber, a spring loaded switch mounted in said chamber, said switch being included in said circuit, a pressure chamber connected to the lubricating system, a pressure responsive element mounted in said pressure chamber, said element being responsive to variations in lubricant pressure and adapted to actuate said switch, a third chamber, a diaphragm located in said third chamber, said third chamber being connected on one side of the diaphragm to the atmosphere, a pipe connecting said third chamber to the intake manifold oi. an engine on the intake side of the throttle, a beak at the end 01' said pipe inside said intake, and a needle valve in said pipe, said needle valve being adapted to adjust the suction action on said diaphragm, said diaphragm being adapted to counteract the action of said pressure responsive element on said switch. DAVID WILLEI'I FLEE'IWOOD DALLIN PAUL. CYRIL HEWELLYN REES.

GEORGE ROBERT WIN 

